Manifold imaging

ABSTRACT

An imaging system wherein a structure comprising a cohesively weak imaging layer sandwiched between a donor sheet and a receiver sheet is employed. The sandwich is placed in an electrical field and exposed to extended imagewise activating electromagnetic radiation. The extended exposure causes the image which conventionally adheres to the receiver sheet to adhere to the donor sheet and the image which conventionally adheres to the donor sheet to adhere to the receiver sheet.

I United States Patent [1 1 [111 3,776,721 Krohn et al. Dec. 4, 1973 MANIFOLD IMAGING Prima Examiner-Charles E. Van Horn 751 t:I T.Khn;GffreA.P- l nven ors zz g alfof Attorney-James J. Ralabate et a1.

9 Rochester, NY.

[73] Assignee: Xerox Corporation, Stamford,

Corm- 57 ABSTRACT [22] Filed: Dec. 18, 1970 An imaging system wherein a structure comprising a [21] Appl' 997l2 cohesively weak imaging layer sandwiched between a Related U.S. Application Data donor sheet and a receiver sheet is employed. The [63] Continuation-impart of Ser. No. 609,124, Jan. 13, Sandwich is Placed in an electrical field and exposed 1967, abandoned. to extended imagewise activating electromagnetic radiation. The extended exposure causes the image [52] U.S. Cl. 96/1 R, 96/1.4 whi nventi n ly a heres to he receiver sheet to [51] Int. Cl. G03 13/22, 603 17/00 adhere to h n r heet n he imag which con- [58] Field of Search 96/1, 1.3, 1.4 ve n lly adher t he donor sheet to adhere to the receiver sheet. [56] References Cited UNITED STATES PATENTS 19 i 7 Drawing Figures 3,556,783 l/l971 Kyriakakis 9611.2

PAIENTEDUEB 4191s 3776.721

- SHEET 10F 2 ACTIVATE SANDWICH APPLY FIELD AND INCREASED EXPOSURE SEPARATE ACTIVATE SANDWICH APPLY FIELD AND EXPOSE SEPARATE F/G-Z I I FIG. 4

MANIFOLD IMAGING This application is a continuation-in-part of our copending application Ser. No. 609,124 filed Jan. 13, 1967 now abandoned.

BACKGROUND OF THE INVENTION The present invention relates in general to imaging and more specifically to a system for the formation of images by layer transfer in image configuration.

Although imaging techniques based on layer transfer of a colored material have been known in the past, these techniques have always been clumsy and difficult to operate because they depend upon photochemical reactions and generally involve the use of distinct layer materials for the two functions of imagewise transfer and image coloration. A typical example of the complex structures and sensitive materials employed in prior art techniques is described in U. S. Pat. No. 3,091,529 to Buskes. A more comprehensive discussion of prior art imaging techniques based on layer transfer may be found in copending application Ser. No. 452,641 filed May 3, 1965 in the U. S. Pat. Office now abandoned.

Copending application Ser. No. 452,641 describes an imaging system utilizing a manifold set comprising a photoresponsive material between a pair of sheets. In this imaging system, an imagable plate is prepared by coating a layer of cohesively weak photoresponsive imaging material onto a substrate. This coated substrate is called the donor. In preparation for the imaging operation, the imaging layer is activated as by treating it with a swelling agent or partial solvent for the material, or by heating. This step may be eliminated, of course, if the layer retains sufficient residual solvent after having been coated on the substrate from a solution or paste. The activating step serves the dual function of making the top surface of the imaging layer slightly tacky and at the same time weakening it structurally so that it can be fractured more easily along a sharp line which defines the image to be reproduced. Once the imaging layer is activated, a receiving sheet is laid down over its surface. An electrical field is then applied across this manifold set while it is exposed to a pattern of light and shadow representative of the image to be reproduced. Upon separation of the donor substrate or sheet and receiving sheet, the imaging layer fractures along the lines defined by the pattern of light and shadow to which the imaging layer has been exposed, with part of this layer being transferred to the receiving sheet while the remainder is retained on the donor sheet so that a positive image, that is, a duplicate of the original is produced on one sheet while a negative image is produced on the other.

At least one of the donor sheet and the receiver sheet is at least partially transparent to permit exposure of the imaging material to the image to be reproduced. The imaging layer serves the dual function of imparting light sensitivity to the system while at the same time acting as colorant for the final image produced. In one form the imaging layer comprises a photosensitive material such as metal-free phthalocyanine dispersed in a cohesively weak insulating binder. The best images are prepared by exposing the manifold set from the donor side of the imaging layer and accordingly, the donor substrate is normally transparent. In addition, the best images are obtained when the exposed portion of the imaging layer is caused to move to the receiver sheet. This means that in prior art systems high quality positive images were obtained only on transparent donor substrate materials. I-Ieretofore, it was not possible to obtain high quality positive images on an opaque material such as paper.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an imaging system which overcomes the above noted disadvantages.

It is another object of this invention to provide a layer transfer imaging system which provides relatively high quality positive images on opaque materials.

It is another object of this invention to provide a system for layer transfer imaging which provides relatively high quality positive images on the receiver sheet.

It is another object of this invention to provide a system for layer transfer imaging which provides relatively high quality positive images on inexpensive opaque receiver materials.

It is another object of this invention to provide a layer transfer imaging system which provides relatively high quality images by transfer of the non-illuminated areas of the imaging layer.

It is another object of this invention to provide a system for layer transfer imaging wherein exposure through the donor layer results in relatively high quality positive images on the receiver sheet.

It is another object of this invention to provide a system for layer transfer imaging which provides a relatively high quality positive image on either donor or receiver sheet.

The above objects and others are accomplished in accordance with this invention by an imaging system wherein a structure comprising a cohesively weak imaging layer sandwiched between a donor sheet and a receiving sheet is employed. An electric potential is placed across the sandwich of donor sheet, imaging layer and receiver sheet and the imaging layer is exposed to light projected from an image to be reproduced resulting in an initial adhesion of negative and positive images to the donor and receiver sheets. The exposure is continued until the image initially adhering to receiver adheres to the donor and the image initially adhering to the donor adheres to the receiver. Convenient ways or means of determining the proper exposure time will be discussed below.

In the prior art the imagewise exposure was continued until high quality images were obtained, which were dependent upon the type of materials employed such as electrically photosensitive pigments and binder materials and the direction of the electric field across the imaging layer. In most instances the initial adhesion produced a positive image on the donor substrate sheet and a negative image on the receiver sheet. This was a result of the exposed area of the imaging layer adhering more strongly to the receiver sheet than it did to the donor sheet whereas the unexposed areas of the imaging layer adhere more strongly to the donor sheet. It has been learned that if the imagewise light exposure is continued beyond the amount required to obtain high quality images a transition phase is reached where increasing amounts of the exposed and unexposed imaging layer reverses their initial adhesion resulting in poor quality images on both donor and receiver sheets. It has been learned further that if imagewise exposure is continued a point is reached where substantially all of the exposed and unexposed areas reverse the initial direction of adhesion. This effect produces a higher quality, positive image on the opposite sheet than would be obtained without overexposure.

The amount of exposure at which image adhesion reversal takes place cannot be predicted. It is known, for example, that the exposure required to produce a high quality, positive image on the receiver sheet varies with the photosensitive pigments, the binders, whether the receiver electrode is biased positive or negative, the purity of the pigments used and the method of manufacturing the imaging layer. However, theamount of exposure required for this invention can be easily determined by the person conducting the experiment by varying the exposure, separating the donor and receiver sheets and observing the amount of background present in each sheet. If the amount of background present is sufficient to interfere with image quality, the experimenter need only increase the exposure by increasing the intensity of the light source, by increasing the time of the exposure or both. The experiment can be simplified by projecting light through a calibrated step wedge light filter which will give a large range of imaging layer exposures in one experiment.

The imaging layer may be exposed either through the donor substrate or through the receiver sheet. Since exposure through the donor substrate allows the use of opaque receiver sheets, it is preferred to expose through the donor substrate. The light image may be formed by passing light through a transparency or by projecting light information from an opaque subject.

The manifold set may include separate electrodes on opposite sides of the donor substrate and receiver sheet for the application of the field or they may be directly on the back surfaces of these members and integral therewith or one or both of the donor substrate and receiver sheet may be made of a conductive material. The donor substrate and the receiving sheet may consist of the same or different materials. Any suitable conductive material may be used for these sheets such as cellophane. Alternatively, these sheets may comprise an insulating material such as polyethylene, polyethylene terephthalate, cellulose acetate and the like, backed by a conductive electrode materials such as evaporated tin oxide. One of these sheets may consist of an opaque material such as paper if desired. Where separate electrodes are used, at least one of the electrodes should be at least partially transparent. Any suitable transparent conductive electrode material may be used. Typical conductive transparent electrode materials include conductively coated glass such as tin or indium oxide coated glass, aluminum coated glass or similar coatings on plastic substrates. Nesa is preferred because of its high transparency and because it is readily available.

The second electrode may be made of any conductive electrode material. Typical conductive electrode materials include metal surfaces such as aluminum, brass, stainless steel, copper, nickel, zinc, etc., conductively coated glass such as tin or indium oxide coated glass, aluminum coated glass, similar coatings on plastic substrates, rubber rendered conductive by the inclusion of a suitable material therein or paper rendered conductive by the inclusion of a suitable chemical therein or through conditioning in a humid atmosphere to insure the presence therein of sufficient water content to render the material conductive. Conductive paper is preferred because of its flexibility.

The basic physical property desired in the imaging layer is that it be frangible or structurally fracturable as prepared or after having been suitably activated. That is, the layer must be sufficiently weak structurally so that the application of electrical field combined with the action of actinic radiation on the electrically photo sensitive materials will fracture the imaging layer. F urther, the layer must respond to the application of field the strength of which is below that field strength which will cause electrical breakdown or arcing across the imaging layer. Another term for cohesively weak, therefore, would be field fracturable."

Where the imaging layer does not have sufi'iciently low cohesive strength at the time of imaging, it must be activated as described above. Typical activating fluids, as further described below, may include any material which will dissolve, partially dissolve or swell or otherwise weaken the imaging layer, thereby reducing its cohesive strength. The activating fluid is ordinarily applied to the imaging layer or to the surface of the receiver sheet which contacts the imaging layer before the imaging operation takes place. Any suitable volatile or non-volatile activating fluid may be employed. Typical materials include kerosene, carbon tetrachloride, petroleum ether, silicone oils, such as dimethylpolysiloxanes, long chain aliphatic hydrocarbon oils such as those ordinarily used as transformer oils, trichloroethylene, chlorobenzene, benzene, toluene, xylene, hexane, acetone, vegetable oils or mixtures thereof. Kerosene is preferred because it is readily available and evaporates quickly.

The imaging layer may comprise any suitable photoresponsive material in a binder. Typical electrically photosensitive materials include materials such as: sub stituted and unsubstituted phthalocyanine; quinacridones; zinc oxide; mercuric sulfide; Algol yellow (C. I. No. 67,300); cadmium sulfide; cadmium selenide; lndofast brillian scarlet (C. I. No. 71,140); zinc oxide; selenium; antimony sulfide; mercuric oxide; indium trisulfide; titanium dioxide; arsenic sulfice; Pb O gallium triselenide; zinc cadmium sulfide; lead iodide; lead selenide; lead sulfide; lead telluride; lead chromate; gallium telluride; mercuric selenide; and the iodides, sulfides, selenides and tellurides of bismuth, aluminum and molybdenum. Organic photoconductors, include those complexed with small amounts (up to about 5 percent) of suitable Lewis acids, such as: 4,5- diphenylimidazolidone; 4,5- diphenylimidazolidinethione; nitrophthalodinitrile; 2- mercaptobenzthiazole; and mixtures thereof. Other organic and inorganic photosensitive materials are described in copending application Ser. No. 708,380 filed Feb. 26, 1968 which is incorporated herein by reference.

Any suitable Lewis acid (electron acceptor) may be employed under complexing conditions with many of the aforementioned more soluble organic materials and also with many of the more insoluble organic materials to impart very important increases in photosensitivity to those materials. Typical Lewis acids are 2,4,7 trinitro-9-fluorenone; 2,4,5,7-tetranitro-9-fluorenone; picric acid; l,3,5-trinitrobenzene, chloranil and benzoquinone. Other Lewis acids are described in the above incorporated copending application Ser. No. 708,380.

In addition, other photoconductors may be formed by complexing one or more suitable Lewis acids with polymers whichare oridinarily not thought of as photoconductors. Typical polymers which may be complexed inthis manner include the following illustrative materials: polyethylene terephthalate, polyamides, polyimides, polycarbonates, polyacrylates, polymethylmethacrylates, polyvinylfiuorides, polyvinyl chlorides, polyvinyl acetates, polystyrene, styrene-butadiene copolymers, polymethacrylates, silicone resins, chlorinated rubber and mixtures and copolymers :thereof where applicable; thermosetting resins such as epoxy resins, phenoxy resins, phenolics, epoxy-phenolic copolymers, epoxy urea formaldehyde copolymers, epoxy melamine-formaldehyde copolymers and mixtures thereof, where applicable. Other typical resins are epoxy esters, vinyl epoxy resins, tall-oil modified epoxies and mixturesthereof where applicable. Phthalocyanines are preferred becauseof their high sensitivity and excellent color. Ofthe phthalocyanines alpha and X forms of metal free phthalocyanine asdescribed in U. S. Pat. No. 3,357,989 have given optimum results. However, any other suitable phthalocyanine may be used where desired.

Any suitable phthalocyanine maybe used to prepare the photoconductive layer I ofthe present invention. The phthalocyanine used may be in any suitable crystal form. It may be substituted or unsubstituted both inthe ring and straight chain portionsReference is madeto a bookentitled Phthalocyanine Compounds byF.H. Moser and A. L. Thomas, published by the Reinhold Publishing Company, l963-edition for a' detailed description of phthalocyanines and their synthesis. Any suitable phthalocyanine may be used in the present-invention. Many other useful phthalocyanines are described in the above incorporated copending-application Ser. No. 708,380.

It is also to be understood in connection with the heterogeneous system, that the photoconductive particles themselves may consist of'any suitable one or more of the aforementioned photoconductors, either organic or inorganic, dispersed in, in solid solution in, or copolymerized with, any suitable insulating resin whether-or not the resin itself is photoconductive. This particular type of particle may be particularly desirable to facili tate dispersion of the particle to prevent undesirable reactions between the binder and the photoconductor or between the photoconductor and the activator and for similar purposes. Typical resins include polyethylene, polypropylene, polyamides, polymethacrylates, polyacrylates, polyvinylchlorides, polyvinyl acetates, polystyrene, polysiloxanes, chlorinated rubbers,.polyacrylonitrile, epoxies, phenolics, hydrocarbon resins and other natural resins such as rosin derivatives as well as mixtures and copolymers thereof. Polyethylene is preferred because it is readily available and electrically insulating.

The binder material inthe heterogeneous imaging layer may comprise anysuitable insulating or photoconductive insulating materials. Typical materials include the insulating resins listed aboveparticularlythe lower molecular weight polyethylenes and polypropylenes; vinyl acetate-ethylene copolymers;styrene-vinyl toluene copolymers; microcrystalline wax; paraffin wax; other lowmolecularweight polymers and copolymers and mixtures thereof.

:6 A mixture of microcrystalline and paraffinic waxes is preferred because it is a good insulator.

DESCRIPTION OF THE DRAWINGS The advantages of this improved method .of imaging will become apparent upon consideration of the detailed disclosure of the invention especially when taken in conjunction withaccompanying drawings wherein:

F IG. 1 is a side sectional view of a photosensitive im- .trating the final process step of this invention distinguishing over the final process step of copending application Ser. No. 708,380.

FIG. 7 is a curve showing the effect of increased exposure on the amount of the exposed imaging layer which adheres to the receiver sheet upon separation of the donor and receiver sheets.

Referring now to FIG. 1, imaging layer 12, comprising photosensitive particles 13 dispersed in binder 14,

is deposited on an insulating donor substrate sheet 17 which is backed with a conductive electrode layer 18. The image receiving portion of the manifold set comprises an insulating receiver sheet 19 backed with a conductive electrode 21. Either or both of the pairs of layer 17, 18 and layers 19 and 21 may be transparent so as to permit exposure of imaging layer 12. The embodiment ofthe invention shown in FIG. 1 is preferred because it allows for the use of high strength insulating polymeric materials as donor substrate sheet 17 and re .ceiver sheet19.

as witha brush, with a smooth or rough surfaced roller,

by flow coating, by vapor condensiton or the like, FIG. 3 which diagrammatically illustrates the first two processsteps, shows the activator fluid .23 being sprayed I onto imaging layer- 12 of the manifold set from a conminer 24. Following the deposition of this activator fluid, the set is closed by a roller 26 which also serves to squeeze .out any excess activator fluid which may have been deposited. The activator serves to swell or otherwise weaken and thereby lower the cohesive strength of imaging layer 12. In certain instances, the

first two steps of the imaging process as disgrammati- -cally-illustrated in FIG. 3 may be omitted; thus, for example, a manifold set which is preactivated during manufacture may be supplied wherein imaging layer 12 is initially fabricated to have a low enough cohesive strength so that activation may be omitted and receiving layer l9may be adhered to the surface of imaging layer 12 at the time when that layer is coated on sub strate 11 either from solution or from a hot melt. It is generally preferable, however, to include an activation step in the process because stronger and more permanent imaging layers may then be provided which can withstand storage and transportation prior to imaging. Once the proper physical properties have been imparted to imaging layer 12 and the receiver sheet 19 has been placed on layer 12, an electrical field is applied across the manifold set through electrodes 18 and 21 as the imaging layer is exposed to the image to be reproduced. Upon separation of substrate 17 and receiving sheet 19, imaging layer 12 fractures along the edges of exposed areas, and at the surface where it had adhered to substrate 17. Accordingly, once separation is complete, exposed portions of imaging layer 12 are retained on one of layers 17 and 19 while unexposed portions are retained on the other layer.

Referring now to the flow diagram of FIG. 5, it is seen that the first two steps of the imaging process are identical to that of the prior art. The third step in the imaging process of this invention is field application and exposure to the light image. It is at this step that the present invention differs from that of the prior art as disclosed in copending application Ser. No. 708,380. In the present invention imagewise exposure is increased to values above those of prior art systems to reverse the imagewise adhesion initially obtained. Upon separation of the manifold set, it is found that the unexposed areas of the imaging layer adhered to the receiver sheet as is shown in FIG. 5. This provides a high quality positive image on receiver sheet 16. Alternatively, in those instances wherein the unexposed portions of the imaging layer adhere initially to the receiver sheet, the increased exposure causes adhesion of such portions to the donor layer.

Referring now to FIG. 7, curves 30 and 40 approximately represent results obtained when using the layers and apparatus of Example I. Curve 30 approximates the results obtained when the receiver sheet electrode is connected to the positive terminal of the power supply; Curve 40 represents results obtained when the receiver sheet electrode is biased negative.

Point 31 and Curve 30 shows that with a total exposure of 30 foot-candle-seconds substantially none of the exposed donor or imaging layer adheres to the receiver sheet when the receiver sheet and donor sheet are separated. On the other hand, substantially all of the substantially non-exposed area of the donor layer adheres to the receiver sheet providing a high quality positive image on the receiver sheet. Point 31 closely represents the results obtained in accordance with Example of this application.

Point 32 on Curve 30 shows that with a total exposure of 0.3 foot-candle-seconds substantially all of the exposed area of the donor layer adheres to the receiver sheet on separation of the receiver and donor sheets. This provides a high quality positive image on the donor sheet and represents the prior art imaging system result. Point 32 closely represents the results obtained in accordance with Example II of this application which Example is intended to show the prior art imaging system as disclosed in copending application Ser. No. 708,380.

Point 41 on Curve 40 represents approximately the result obtained when the receiver sheet electrode is connected to the negative terminal on the power supply and the imaging layer is exposed to a total incident energy of about 2 foot-candle-seconds. Substantially none of the exposed donor layer adheres to the receiver sheet. Since substantially all of the unexposed donor laye adheres to the receiver sheet, a high quality positive image is obtained on the receiver sheet. Point 41 closely represents the results obtained in accordance with Example III of this application.

Point 42 on Curve 40 represents the results obtained when the imagewise exposure totals 0.3 foot-candleseconds. Substantially all of the exposed area of the donor layer adheres to the receiver sheet leaving behind a high quality, positive image on the donor layer. This closely represents the result obtained in accordance with the experiment of Example IV of this application. Point 42 and Example IV represent the prior art imaging system. Normally exposure in the range of from 2 to about 20 times that required for initial adhesion of the imaging layer is required for reversal of adhesion in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following Examples further specifically illustrate the present invention. The Examples below are intended to illustrate various preferred embodiments of the improved imaging method. The parts and percentages are by weight unless otherwise indicated.

EXAMPLE I A commercial metal-free phthalocyanine is first purified by o-dichlorobenzene extraction to remove organic impurities. Since this extraction step yields the less sensitive beta crystalline form, the desired 1: form is obtained by dissolving about I00 grams of beta in approximately 600 cc of sulfuric acid precipitating it by pouring the solution into about 3,000 cc. of ice water and washing with water to neutrality. The thus purified alpha phthalocyanine is then salt milled for 6 days and desalted by slurrying in distilled water, vacuum filtering, water washing, and finally methanol washing until the initial filtrate is clear. After vacuum drying to remove residual methanol, the x form phthalocyanine thus produced is used to prepare the imaging layer according to the following procedure: About 5 grams of the x form phthalocyanine is added to about 5 grams of Algol Yellow GC, l,2,5,6-di-(C,C'- diphenyl) thiazole-anthraquinone, C. I. No. 67300, available from General Dyestuffs, and about 2.8 grams of purified Watchung Red B, 1-(4'-methyl-5- chloroazobenzene-Z-sulfonic acid)-2-hydroxy-3- naphthoic acid, C. I. No. 15865, available from E. l. du- Pont de Nemours & Co., which is purified as follows: approximately 240 grams of the Watchung Red B is slurried in about 2,400 milliliters of Sohio Odorless Solvent 3440, a mixture of kerosene fractions available from the Standard Oil Company of Ohio. The slurry is then heated to a temperature of about 65C. and held there for about one-half hour. The slurry is then filtered through a glass sintered filter. The solids are then reslurried with petroleum ether (-l20C.) available from Matheson Coleman and Bell Division of the Matheson Company, East Rutherford, New Jersey and filtered through a glass sintered filter. The solids are then dried in an oven at about 50C.

About 8 grams of Sunoco Microcrystalline Wax Grade 5825 having an ASTM-D-l27 melting point of llF. and about 2 grams of Paraflint R. G., a low molecular weight paraffmic material available from the Moore & Munger Company, New York City and about 320 milliliters of petroleum ether (90-l20C.) and about 40 milliliters of Sohio Odorless Solvent 3440 are placed with the pigments in a glass jar containing onehalf inch flint pebbles. The mixture is then milled by revolving the glass jar at about 70 rpm. for about 16 hours. The mixture is then heated for approximately 2 hours at about 45C. and allowed to cool to room temperature. The mixture is then ready for coating on the donor substrate. The paste-like mixture is then coated in subdued green light on 2 mil Mylar (a polyester formed by the condensation reaction between ethylene glycol and terephthalic acid available from E. I. duPont de Nemours & Co., Inc.) with a No. 36 wire wound drawdown rod to produce a coating thickness when dried of approximately 7 /5 microns. The coating and 2 mil Mylar sheet is then dried in the dark at a temperature of about 33C. for one-half hour. The coated donor is then placed on the tin oxide surface of a oneeighth inch N esa glass plate with its coating facing away from the tin oxide. A receiver sheet also of 2 mil Mylar is placed over the donor. A sheet of black electrically conductive paper available as grade 505 black photographic paper from Knowlton Paper Company, Watertown, New York is placed over the receiver sheet to form the complete manifold set. The receiver sheet is I then lifted up and the imaging layer activated with one brush stroke of a wide camels hair brush saturated with Sohio 3440. The receiver sheet is then lowered back down and a roller is rolled slowly once over the closed manifold set with light pressure to remove excess solvent. The negative terminal of a 9,000 volt DC power supply is then connected to the Nesa coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque electrode and grounded. With the voltage applied, a white incandescent light image is projected through the Nesa glass using a 300 watt Bell and Howell Headliner Model 708 Duo Slide Projector having a piece of Trans-Positive Sheet (Frosted) available from Xerox of Rochester, New York and a variable aperature placed in front of it. The distance from the projector to the imaging donor layer is approximately 60 inches. The light incident on the imaging layer is adjusted to approximately 30 foot-candles. The imagewise exposure is continued for about 1 second resulting in an application of total incident energy on the imaging layerof about 30 footcandleseconds. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image on the-donor sheet.

EXAMPLE ll PRIOR ART By way of contrast, the experiment of Example I is repeated except that the imaging layer is exposed to an intensity of about 1 foot-candle for about 0.3 seconds. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images wih a positive image adhering to the donor sheet and a negative image adhering to the receiver sheet. Example I] is included to show the results obtained using prior art imaging methods.

EXAMPLE Ill The experiment of Example I is repeated except that the Nesa is connected to the positive terminal of the power supply and the negative terminal connected to the black opaque electrode and grounded. An imagewise exposure of about 2 seconds is used at an intensity of l foot-candle resulting in application of total incident energy on the imaging layer of about 2 footcandle-seconds. The receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yeilding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE IV PRIOR ART The experiment of Example III is repeated except that the imagewise exposure is continued for 0.3 seconds resulting in application of total incident energy on the imaging layer of about 0.3 foot-candle-seconds. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the donor sheet and a negative image adhering to the receiver sheet. Example IV is included to show the results obtained using prior art imaging techniques.

EXAMPLE V About 2 /2 grams of .r" form phthalocyanine prepared as in Example I, about 2 grams of Benzidine Yellow YT-4l l available from the Holland Suco Co., Holland, Michigan and approximately 60 cc. of the pe troleum ether of Example I are placed in a glass jar with one-half inch flint pebbles and milled as in Example I for about 16 hours.

Next, about 1 mol of alpha methyl styrene and about 1 mol of vinyl toluene are added to sufficient xylene to produce a 40 percent solution. A catalytic amount of Boron trifluoride etherate is then added and the mixture stirred until polymerization is complete. After polymerization, sufficient methanol is added to decompose any boron trifluoride present, the polymer is then isolated by steam distillation. The resulting polymer is available as Piccotex from the Pennsylvania lndustrial Chemical Company.

About 2 B grams of the Piccotex 100 is added to about 3 grams of polyethylene DYLT available from the Union Carbide Company, and about 1 grams of Paraflint RG and about one-half gram of Elvax 420 an ethylene-vinyl-acetate copolymer available from the E. I. duPont de Nemours Company. The mixture is then dissolved in about 20 milliliters of Sohio 3440 at about the boiling point. The solution is then allowed to cool to room temperature. The solution is then added to the mixture of pigments and milled as in Example I for about 16 hours. The milled mixture is then heated to a temperature of approximately 65C for approximately 2 hours and then allowed to cool to. approximately room temperature. About 60 milliliters of reagent grade isopropanol is then added to the mixture and the mixture milled for about 15 more minutes. The resulting paste is then ready for coating on the donor substrate. The paste is then coated in subdued green light on two mil Mylar with a No. 36 wire wound drawdown rod to produce a coating thickness dry of about 7 V2 microns. The coated donor is then heated in the dark to about 33C. for about one-half hour in order to dry it. The coated donor is then placed on the tin oxide surface of a Nesa glass plate with its coating facing away from the tin oxide. A receiver sheet of polyethylenev coated paper Grade 1230.3 available from Crocker Hamilton Paper Company, Fitchburg, Mass. is placed with the polyethylene side down over the donor layer. Then a one-sixteenth inch thick sheet of conductive Neoprene No. 5084 available from the Buffalo Belting and Weaving of Buffalo, New York, is placed over the receiver sheet to form the complete manifold set. The receiver sheet is then lifted up and the imaging layer activated with one quick brush stroke of a wide camels hair brush saturated with Sohio 3440.' The receiver sheet is then lowered back down and a roller is roller slowly once over the closed manifold set with light pressure to remove any excess Sohio. The negative terminal of an 8,000 volt DC power supply is then connected to the Nesa coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque neoprene electrode and grounded.

With the voltage applied an image is projected onto the manifold set as in Example I. lmagewise exposure is continued for about 1 second at an intensity of 8 footcandles resulting in application of total incident energy of about 8 foot-candle-seconds on the imaging layer. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE Vl PRlOR ART The experiment of Example V is repeated except that imagewise exposure is continued for 0.4 seconds at an intensity of about I foot-candle resulting in a total incident energy of about 0.4 foot-candle-seconds applied to the imaging layer. After exposure, the receiver sheet is peeled from the setwith the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the donor sheet and a negative image adhering to the receiver sheet. Example Vl is included to show the results obtained under prior art imaging techniques.

EXAMPLE Vll About 2 A grams of the x" form of phthalocyanine prepared as in Example I, about 1.2 grams of Algol Yel low and about 2.8 grams of lrgazine Red available from the Geigy Chemical Company are added to about 120 milliliters of petroleum ether, 90l 20C, and milled as in Example I for about 16 hours. The mixture is then added to the binder of Example V and milled as in Example l for about 16 hours. The mixture is heated to a temperature of approximately 65C. for approximately 2 hours. It is then allowed to cool to approximately room temperature. The paste is then ready for coating on a donor substrate. The paste is then coated in subdued green light on 2 mil Mylar with a No. 36 wire wound drawdown rod to produce a coating thickness dry of about 7 :6 microns. The donor is then dried in the dark at a temperature of about 33C. for about 30 minutes. The coated donor is then placed on the tin oxide surface of a Nesa glass plate with its coating facing away from the tin oxide. A receiver sheet of Xerox 400 bond paper available from Xerox Corporation is placed over the donor layer. Then, a sheet of the black electrically conductive paper of Example I is placed ovr the receiver sheet to form the complete manifold set. The receiver sheet is then lifted up and the imaging layer activated with one quick brush stroke of a wide camels hair brush saturated with Sohio 3440. The receiver sheet is then lowered back down and a roller is rolled slowly once over the closed manifold set with light pressure to remove excess Sohio. The negative terminal of an 8,000 volt DC power supply is then connected to the Nesa coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque electrode and grounded. With the voltage applied, an image is projected onto the imaging layer as in Example I. The imagewise exposure is continued for about 1 second at an intensity of 30 footcandles resulting in the application of a total incident energy of about 30 foot-candle-seconds on the imaging layer. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The

. small amount of Sohio present evaporated after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE Vlll PRIOR ART The experiment of Example Vll is repeated except that the imagewise exposure is continued for a total of about 0.35 seconds at an intensity of l foot-candle, resulting in a total incident energy application of about 0.35 foot-candle-seconds on the imaging layer. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the donor sheet and a negative image adhering to the receiver sheet. Example VIII is included to show the'results obtained under prior art imaging techniques.

EXAMPLE lX About 3 grams of x form phthalocyanine prepared as in Example I and about 60 milliliters of petroleum ether, -l20C, are milled as in Example I for about l6 hours. A binder is prepared as in Example V with the exception that the polyethylene prepared as in Example V with the exception that the polyethylene DYLT is replaced with Epolene C10, a low molecular weight polyethylene available from the Eastman Kodak Company. The pigment mixture and binder are then processed as in Example V. The experiment of Example l is then repeated except that the imagewise exposure continues for about 1 second at an intensity of about 3.5 foot-candles resulting in application of total incident energy of about 3.5 foot-candle-seconds on the imaging layer. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE X PRIOR ART EXAMPLE Xl An imaging layer comprising electrically photosensitive materials dispersed in a binder is first prepared. About 100 parts of Napthol Red B, code 20-7575 available from American Cyanamide Company is dissolved in reagent grade ethylenediamine. The solution is filtered immediately through course filter paper and the filtrate mixed with an equal volume of reagent grade isopropanol. The Naphthol Red B precipitates in the alcohol and is removed by means of a centrifuge. After separating the ethylenediamine and alcohol, the electrically photosensitive material is washed and filtered with successive amounts of isopropanol, a 2:1 volume mixture of isopropanol and deionized water and five washings with deionized water until the filtrate is neutral. Finally, the material is washed with dimethylformamide and methanol in succession until the filtrates have a pale yellow color. The Naphthol Red B is then dried at 40C. under vacuum. About 2.5 parts of the purified Napthol Red B is combined with about 0.5 parts of Benz Yellow, code 30-0535 available from the Hilton Davis Chemical Company. The Benz Yellow is purified by solvent extraction in an organic solvent. The Naphthol Red B and Benz Yellow are combined with about 45 parts of naptha and ball milled for 4 hours.

A binder material is prepared by combining about 2.5 parts of Paraflint RG, a low molecular weight parafinic material available from the Moore and Munger Co., New York City; about 3 parts of Polyethylene DYLT available from Union Carbide Corporation; about 0.5 parts of a vinyl acetate-ethylene copolymer available as Elvax 420 from E. l. duPont de Nemours inc. and about 2.5 parts of a modified polystyrene available as Piccotex 100 from Pennsylvania Industrial Chemical Co. with about parts of Sohio Odorless Solvent 3440 a kerosene fraction available from the Standard Oil Company. The mixture is heated until dis- .solved and then cooled. The binder and pigment mixtures are then ball milled for a period of about 18 hours. About 45 partsof isopropyl alcohol is added to the mixture and the mixture is milled in the ball mill for 15 minutes. The resulting imaging material is then coated on 3 mil Mylar with a doctor knife set at a gap of 4.4 mil to produce a donor. The donor is dried at a temperature of about 1 15F.

The donor is then placed on the tin oxide surface of a Nesa glass plate with the imaging layer facing away from the tin oxide. The imaging layer is activated by applying Sohio Odorless Solvent 3440 by means of a brush and a sandwich is formed by placing a transparent film of polypropylene over the activated donor as a receiver. A black paper electrode is laid over the receiver sheet and a 10,000 volt DC negative potential is applied to the Nesa while the paper electrode is connected to the positive side of the power supply. The imaging layer is exposed to a pattern of light from an incandescent white light source of 30 foot-candles for a period of 1 second through the transparent donor. With the potential applied, the receiver is separated from the donor thereby fracturing the imaging layer and revealing a positive image adhering to the donor sheet and a negative image on the receiver sheet.

EXAMPLE Xll PRIOR ART The procedure of Example X] is repeated except that the exposure was continued only 0.33 seconds to provide a total exposure of about 10 foot-candle-second on the imaging layer. Upon separation of the sheets, a

pair of images are observed with the positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

Although specific components and proportions have been stated in the above description of preferred embodiments of the invention, other typical materials as listed above if suitable may be used with similar results. In addition, other materials may be added to the mixture to synergize, enhance or otherwise modify the properties of the imaging layer. For example, various dyes, spectral sensitizers or electrical sensitizers such as Lewis Acids may be added to the several layers.

Other modifications and ramificiations of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.

What is claimed is:

l. A method of imaging comprising:

a. providing an electrically photosensitive imaging layer sandwiched between a donor sheet and receiving sheet, said imaging layer being structurally fracturable in response to the combined effect of an applied electric field and exposure to electromagnetic radiation to which said layer is sensitive; at least one of said donor and receiving sheets being at least partially transparent to said radiation;

b. maintaining an electric field across said imaging layer;

c. exposing said imaging layer to a pattern of activating electromagnetic radiation whereby said exposed areas of said layer adhere to one of said donor and receiving sheets and the unexposed areas of said layer to the other sheet;

d. continuing said exposure until a substantial portion of the unexposed areas of said imaging layer adhering to one of said donor and receiving sheets adhere to the opposite sheet and a substantial portion of the exposed areas of said imaging layer adhering to one of said donor and receiving sheets adhere to the opposite sheet; and,

e. separating said receiving sheet while under said field from said donor sheet whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on one of said donor and receiving sheets and a negative image of the original on the other sheet.

2. The method of claim 1 wherein said donor sheet is at least partially transparent and said imaging layer is exposed through said donor sheet.

3. The method of claim I wherein said receiver sheet is at least partially transparent and said imaging layer is exposed through said receiving sheet.

4. The method of claim 1 further including the step of applying an activator to said imaging layer prior to its exposure.

5. The method of claim 1 wherein said imaging layer comprising metal-free phthalocyanine in a binder.

6. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in the X crystalline form in a binder.

7. The method of claim 1 wherein said imaging layer comprises a mixture of photosensitive pigments in a binder.

8. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising an insulating composition.

9. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising a thermoplastic insulating composition.

10. The method of claim 1 wherein said imaging layer comprises an organic electrically photosensitive material.

II. The method of claim 10 wherein the said electrically photosensitive material is dispersed in a binder.

12. A method of imaging comprising:

a. providing an imaging layer sandwiched between a donor sheet and a receiving sheet, said imaging layer being structurally fracturable in response to the combined effect of an applied electric field and exposure to electromagnetic radiation to which said layer is sensitive; at least one of said donor and receiving sheets being at least partially transparent to said radiation;

b. maintaining an electric field across said imaging layer;

c. exposing said imaging layer to a pattern of activating electromagnetic radiation, whereby a substantial portion of the substantially exposed areas of said imaging layer adhere to the receiving sheet and a substantial portion of the unexposed areas of said imaging layer adhere to the donor sheet;

d. continuing said exposure until a substantial portion of the unexposed areas of said imaging layer adhering to said donor sheet adhere to the receiving sheet and a substantial portion of the exposed areas adhere to the donor sheet; and,

e. separating said receiving sheet from said donor sheet while under said field whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on the receiver sheet.

13. The method of claim 12 further including the step of rendering said imaging layer structurally fracturable in response to the combined effect of an electric field and exposure to electromagnetic radiation to which said layer is sensitive by contacting said layer with an activating amount of an activator prior to its exposure.

14. The method of claim 12 wherein said imaging layer comprises an organic electrically photosensitive material.

15. The method of claim 14 wherein the electrically photosensitive material is dispersed in a binder.

16. A method of imaging comprising:

a. providing an imaging layer sandwiched between a donor sheet and a receiving sheet, said imaging layer being structurally fracturable in response to the combined effect of an applied electric field and exposure to electromagnetic radiation to which said layer is sensitive; at least one of said donor and receiving sheets being at least partially transparent to said radiation;

b. maintaining an electric field across said imaging layer;

c. exposing said imaging layer to a pattern of activating electromagnetic radiation, whereby a substantial portion of the substantially exposed areas of said imaging layer adhere to the donor sheet and a substantial portion of the unexposed areas of said imaging layer adhere to the receiving sheet;

d. continuing said exposure until a substantial portion of the unexposed areas of said imaging layer adhering to said receiver sheet adhere to the donor sheet and a substantial portion of the exposed areas adhere to the receiving sheet; and,

e. separating said receiving sheet from said donor sheet while under said field whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on the donor sheet.

17. The method ofclaim 16 further including the step of rendering said imaging layer structurally fracturable in response to the combined effect of an electric field and exposure to electromagnetic radiation to which said layer is sensitive by contacting said layer with an activating amount of an activator prior to its exposure.

18. The method of claim 16 wherein said imaging layer comprises an organic electrically photosensitive material.

19. The method of claim 18 wherein the electrically photosensitive material is dispersed in a binder.

* in k a 

2. The method of claim 1 wherein said donor sheet is at least partially transparent and said imaging layer is exposed through said donor sheet.
 3. The method of claim 1 wherein said receiver sheet is at least partially transparent and said imaging layer is exposed through said receiving sheet.
 4. The method of claim 1 further including the step of applying an activator to said imaging layer prior to its exposure.
 5. The method of claim 1 wherein said imaging layer comprising metal-free phthalocyanine in a binder.
 6. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in the X crystalline form in a binder.
 7. The method of claim 1 wherein said imaging layer comprises a mixture of photosensitive pigments in a binder.
 8. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising an insulating composition.
 9. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising a thermoplastic insulating composition.
 10. The method of claim 1 wherein said imaging layer comprises an organic electrically photosensitive material.
 11. The method of claim 10 wherein the said electrically photosensitive material is dispersed in a binder.
 12. A method of imaging comprising: a. providing an imaging layer sandwiched between a donor sheet and a receiving sheet, said imaging layer being structurally fracturable in response to the combined effect of an applied electric field and exposure to electromagnetic radiation to which said layer is sensitive; at least one of said donor and receiving sheets being at least partially transparent to said radiation; b. maintaining an electric field across said imaging layer; c. exposing said imaging layer to a pattern of activating electromagnetic radiation, whereby a substantial portion of the substantially exposed areas of said imaging layer adhere to the receiving sheet and a substantial portion of the unexposed areas of said imaging layer adhere to the donor sheet; d. continuing said exposure until a substantial portion of the unexposed areas of said imaging layer adhering to said donor sheet adhere to the receiving sheet and a substantial portion of the exposed areas adhere to the donor sheet; and, e. separating said receiving sheet from said donor sheet while under said field whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on the receiver sheet.
 13. The method of claim 12 further including the step of rendering said imaging layer structurally fracturable in response to the combined effect of an electric field and exposure to electromagnetic radiation to which said layer is sensitive by contacting said layer with an activating amount of an activator prior to its exposure.
 14. The method of claim 12 wherein said imaging layer comprises an organic electrically photosensitive material.
 15. The method of claim 14 wherein the electrically photosensitive material is dispersed in a binder.
 16. A method of imaging comprising: a. providing an imaging layer sandwiched between a donor sheet and a receiving sheet, said imaging layer being structurally fracturable in response to the combined effect of an applied electric field and exposure to electromagnetic radiation to which said layer is sensitive; at least one of said donor and receiving sheets being at least partially transparent to said radiation; b. maintaining an electric field across said imaging layer; c. exposing said imaging layer to a pattern of activating electromagnetic radiation, whereby a substantial portion of the substantially exposed areas of said imaging layer adhere to the donor sheet and a substantial portion of the unexposed areas of said imaging layer adhere to the receiving sheet; d. continuing said exposure until a substantial portion of the unexposed areas of said imaging layer adhering to said receiver sheet adhere to the donor sheet and a substantial portion of the exposed areas adhere to the receiving sheet; and, e. separating said receiving sheet from said donor sheet while under said field whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on the donor sheet.
 17. The method of claim 16 further including the step of rendering said imaging layer structurally fracturable in response to the combined effect of an electric field and exposure to electromagnetic radiation to which said layer is sensitive by contacting said layer with an activating amount of an activator prior to its exposure.
 18. The method of claim 16 wherein said imaging layer comprises an organic electrically photosensitive material.
 19. The method of claim 18 wherein the electrically photosensitive material is dispersed in a binder. 